Age-validation and growth of bluefish ( Pomatomus saltatrix) along the East Coast of the United States

Abstract

We examine the age and growth of bluefish, Pomatomus saltatrix, along the U.S. east coast collected from Florida to New York during 2001–2003 ( n = 2652). We describe a new preparation technique for the otoliths that increases readability, and provide criteria for the interpretation of otolith microstructure. Annulus formation in otoliths for bluefish is validated for fish aged 1–8 using marginal increment analysis. This extends validation by 4 years to include the preponderance of age classes in the catch. A side-by-side comparison of ageing precision and bias was performed between otoliths and scales. When compared, precision was highest with sectioned otoliths, exceeding 87% across all years, and exceeding 99% within 1 year, up to age 13. In contrast, scales tended to over-age ages 1 through 5, and under-aged age 7 and older compared to sectioned otoliths. We used these otolith-based ages to evaluate age distribution in gears used in the fishery and to evaluate size-at-age data and to estimate growth parameters from the catch. No significant differences in the von Bertalanffy growth parameters were found in comparison by sex, year and between the South Atlantic and Middle Atlantic Bights using Kimura's likelihood-ratio test. The estimated von Bertalanffy model growth parameters for bluefish along the coast were L inf = 815.3 mm ±15.3, k = 0.311 ± 0.03, t 0 = −0.301 ± 0.18. These findings are then used to examine the implications for management of this ecologically and economically important coastal pelagic species.